我在用JdbcTemplate
从数据库中检索 Bean。这是我的方法:
public List<trackerv3Livedata> getTrackerData() {
return List<trackerv3Livedata> live = (List<trackerv3Livedata>) jdbcTemplate.queryForList("select * from mmitrackerv3_livedata where accountid =?",new Object[]{aid}, trackerv3Livedata.class);
}
trackerv3Livedata bean结构如下:
public class trackerv3Livedata implements Serializable {
private static final long serialVersionUID = 2409168269491619888L;
private int deviceid;
private Long timestamp;
private Mmitrackerv3Device mmitrackerv3Device;
private Mmitrackerv3Account mmitrackerv3Account;
private double latitude;
private double longitude;
private Double altitude;
private Double speedkph;
private Double heading;
private Double gpssignal;
private Integer geozoneid;
private Double distancekm;
private Double gsmsignal;
private Double mainpower;
private Integer laststatustime;
private Double internalbattry;
private Double temperature;
private Short dinput1;
private Short dinput2;
private Short dinput3;
private Short dinput4;
private Short dinput5;
private Short dinput6;
private Short dinput7;
private Short dinput8;
private Short ainput1;
private Short ainput2;
private Short ainput3;
private Short ainput4;
private Short doutput1;
private Short doutput2;
private Short doutput3;
private Short doutput4;
/* There are Some Getter And Setter Method With Constructor */
}
在我的场景中,我的查询完全有可能不会被命中,所以我的问题是如何解决以下错误消息。
org.springframework.jdbc.IncorrectResultSetColumnCountException: Incorrect column count: expected 1, actual 38
在我看来,我应该返回一个 null 而不是抛出异常。我怎样才能解决这个问题?提前致谢。
Jdbc模板方法
queryForList(String sql, Class<T> elementType)
对以下有用单列查询,您只能指定列类型。如果您需要 ResultSet 中的多列,则使用更准确
query(String sql, RowMapper<T> rowMapper)
作为 RowMapper 的实现,您可以使用自己的,或者
jdbcTemplate.query(sql, new BeanPropertyRowMapper<T>(clazz));
所以在你的情况下可能是:
public List<Trackerv3Livedata> getTrackerData() {
String sql = "SELECT * FROM mmitrackerv3_livedata mlive " +
"JOIN mmitrackerv3_device mdevice ON mlive.accountid = " +
"mdevice.accountid WHERE mlive.accountid = " + aid;
return jdbcTemplate.query(sql,
new BeanPropertyRowMapper<Trackerv3Livedata>(Trackerv3Livedata.class));
}
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